Method for fabricating microfluidic structures

ABSTRACT

A method for fabricating microfluidic structures is provided. The method includes: a belt is provided and an adhesion layer is formed on at least one surface of the belt; the belt is cut for forming a first microfluidic channel thereon, wherein the first microfluidic channel has an accommodating space; a second microfluidic channel is provided, wherein a line-width of the second microfluidic channel is smaller than a line-width of the first microfluidic channel; the second microfluidic channel is disposed in the accommodating space of the first microfluidic channel; and a substrate is adhered to the belt via the adhesion layer.

RELATED APPLICATIONS

The present application is a Divisional Application of the U.S.application Ser. No. 15/582,750, filed Apr. 30, 2017, which is aDivisional Application of the U.S. application Ser. No. 14/266,820,filed on Apr. 30, 2014, U.S. Pat. No. 9,682,374 issued on Jun. 20, 2017,and claims priority to Taiwan application serial number 103102130, filedJan. 21, 2014, the entire contents of which are hereby incorporatedherein by reference.

BACKGROUND Technical Field

The present disclosure relates to a method for fabricating microfluidicstructures, especially relates to a method for fabricating microfluidicstructures that patterns of the microfluidic structure are formed byutilizing pre-patterned double-sided tape, thereby extra packagingprocess is not required.

Description of Related Art

There exists a plurality of small-scaled materials in a natural world.For testing and researching these materials, small components havingdimensions as low as μm or nm order are required. Conventionally, it isvery difficult to fabricate devices equipped with such small-scaledcomponents. Recently, as the progress on the science and themanufacturing technology, it is possible to fabricate devices equippedwith such small-scaled components.

Microfluidic devices are widely used in biomedical equipment, fuelcells, heat exchangers, chromatography sensors and printer heads.Briefly speaking, the microfluidic structures are provided for a fluidto flow therein in order to transport or filter micro-materials in thefluid. In some cases, multi fluids are mixed in a microfluidic structurefor observing reactions between many micro-materials, and achievingrapid transportation and testing. Recently, the microfluidic structuresare widely used in biomedicine fields, for example, to utilizemicrofluidic structure to test or filter proteins or stem cells.

The fluid is not easily flowed in a microfluidic structure owing to theultra-small dimension of the microfluidic structure. In a situation thatwithout applying any outer driving forces, the fluid can only be drivenby diffusion or capillarity effect. To the micro-materials with lowdiffusion coefficient (e.g. proteins), it will take a lot of time onflowing and mixing it to another micro-materials.

For solving issues on low fluidity of the fluids in microfluidicstructures, many methods are provided for increasing diffusion rate ofthe fluids. In one method, the microfluidic structure are patterned toform complicated structures in order to increase contact area, therebydecreasing the diffusion length thus the diffusion rate can beincreased. The aforementioned patterned microfluidic structure can alsobe applied extra driving forces such as voltage, electric field,pressure or micro-pump for driving the fluid.

Although the aforementioned patterned microfluidic structures can solveissues on low fluidity of the fluid, however, the original dimension ofthe microfluidic structure itself is very small. If complicated patternsare formed on the microfluidic structures, complicated processes arerequired, thereby leading to high manufacturing cost and time.

For example, FIG. 1 is a schematic view showing a conventionalfabricating process for a microfluidic structure. In FIG. 1, aphoto-sensitive material 120 is deposited on a substrate 110. Then, aphotolithography process is applied to the photo-sensitive material 120to form patterns for the microfluidic structure. Then, a metal layer 130is deposited on the patterned photo-sensitive material 120, and anetching process is performed to remove the photo-sensitive material 120.The metal layer 130 is then patterned and formed on the substrate 110.The structure of the substrate 110 having the patterned metal layer 130deposited thereon is called a master mold. After the master mold isformed, a gel-type material 140 which being solidified after heating isinjected into the master mold, and the gel-type material 140 ispatterned by the patterned metal layer 130. Finally, a patternedmicrofluidic structure is formed. Followed by cutting and bondingprocesses, a complete microfluidic device 150 is fabricated.

The aforementioned section discloses a conventional fabricating methodfor microfluidic structures. Although other fabricating methods aredeveloped, the basic concept is similar with the aforementioned case.These kinds of processes are very complicated and related materials andequipment thereof are expensive as well as the fabricating time is long.

SUMMARY

According to one aspect of the present disclosure, a method forfabricating microfluidic structures includes: a belt is provided and anadhesion layer is formed on at least one surface of the belt; the beltis cut for forming a first microfluidic channel thereon, wherein thefirst microfluidic channel has an accommodating space; a secondmicrofluidic channel is provided, wherein a line-width of the secondmicrofluidic channel is smaller than a line-width of the firstmicrofluidic channel; the second microfluidic channel is disposed in theaccommodating space of the first microfluidic channel; and a substrateis adhered to the belt via the adhesion layer.

According to another aspect of the present disclosure, a method forfabricating microfluidic structures includes: a first belt is providedand an adhesion layer on at least one surface of the first belt; thefirst belt is cut for forming a first microfluidic channel, wherein thefirst microfluidic channel has a first depth; a second belt is providedand an adhesion layer is formed on at least one surface of the secondbelt; the second belt is cut for forming a second microfluidic channel,wherein the second microfluidic channel has a second depth; the firsbelt and the second belt is adhered via the adhesion layer; and thefirst belt and the second belt are stacked in order to stack the firstdepth and the second depth.

According to still another aspect of the present disclosure, a methodfor fabricating microfluidic structures includes: a double-sided tape isprovided, wherein the double-sided tape has an adhesion layer and atleast one protecting layer outside of the adhesion layer, and theadhesion layer has at least one adhering surface; patterned-microfluidicchannels is formed on the adhesion layer via a knife mold withpre-determined patterns; the protecting layer is removed for exposingthe adhering surface; and a substrate is adhered to the adheringsurface.

According to further another aspect of the present disclosure, a methodfor fabricating microfluidic structures includes: a double-sided tape isprovided, wherein the double-sided tape has an intermediate layer, twoadhesion layers located at a top side and a bottom side of theintermediate layer and two protecting layers located at outside of eachadhesion layer, wherein each adhesion layer has at least one adheringsurface; patterned-microfluidic channels are formed on the intermediatelayer via a knife mold with pre-determined patterns; the protectinglayer is removed for exposing the adhering surface and a substrate isadhered to the adhering surface.

According to one aspect of the present disclosure, a method forfabricating microfluidic structures includes: a belt is provided; thebelt is cut via a knife mold with pre-determined patterns, a firstmicrofluidic channel and an aligning area are formed on one portion ofthe belt, and an aligning mark is formed on the other portion of thebelt, wherein the aligning area has an indentation; and the belt isfolded for stacking the two portions thereof and the aligning mark isembedded to the indentation.

According to one aspect of the present disclosure, a method forfabricating microfluidic structures includes: a belt is provided; thebelt is cut via a knife mold with pre-determined patterns, the belt isseparated into tow portions by a folding line, a first microfluidicchannel and an aligning area are formed on one portion of the belt, andan aligning mark is formed on the other portion of the belt, wherein thealigning area has an indentation; and the belt is folded for stackingthe two portions thereof and the aligning mark is embedded to theindentation in accordance with the folding line.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be more fully understood by reading the followingdetailed description of the embodiment, with reference made to theaccompanying drawings as follows:

FIG. 1 is a schematic view showing a conventional fabricating processfor a microfluidic structure;

FIG. 2 is a schematic view showing a method for fabricating microfluidicstructures according to one embodiment of the present disclosure;

FIG. 3 is a structural view showing a knife mold used in the method ofFIG. 2;

FIG. 4 is a structural view showing a complete product fabricated by themethod of FIG. 2;

FIG. 5 is a schematic view showing another embodiment of the method ofFIG. 2;

FIG. 6A to FIG. 6C are schematic views showing a method for fabricatingmicrofluidic structures according to another embodiment of the presentdisclosure;

FIG. 7A is a schematic view showing a method for fabricatingmicrofluidic structures according to still another embodiment of thepresent disclosure;

FIG. 7B is a schematic view showing another example of the folding lineof FIG. 7A;

FIG. 8 is a schematic view showing a method for fabricating microfluidicstructures according to further another embodiment of the presentdisclosure; and

FIG. 9 is a schematic view showing a method for fabricating microfluidicstructures according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the present embodiments of thedisclosure, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

The present disclosure provides a method for fabricating microfluidicstructures. Cutting a belt (e.g. single-sided tape or double-sided tape)with adhesion layer thereon, and forming microfluidic structure on thebelt. By the adhesion layer of the belt, the microfluidic structure canbe adhered to a substrate directly, thus a complete and usefulmicrofluidic device is rapidly formed.

FIG. 2 is a schematic view showing a method for fabricating microfluidicstructure 200 according to one embodiment of the present disclosure.FIG. 3 is a structural view showing a knife mold 210 used in the methodof FIG. 2. Knife mold 210 is utilized for cutting a belt 220. Apre-patterned knife 211 is formed on the knife mold 210. In theembodiment, the belt 220 is a double-sided tape. The belt 220 includesadhesion layers 222, 223, intermediate layer 221 and protection layers224, 225. The adhesion layers 222, 223 are formed on a top side and abottom side of the intermediate layer 221 respectively. The protectionlayer 224 is formed on a top side of the adhesion layer 222 and theprotection layer 225 is formed on a bottom side of the adhesion layer223 for temporary protection. First, the belt 220 is cut by the knife211. The protection layers 224, 225, the intermediate layer 221 and theadhesion layers 222, 223 are cut through. Owing to the knife 211 haspre-determined patterns, microfluidic channels 240 with pre-determinedpatterns are formed on a portion of the belt 220 that being cut throughby the knife 211. Each of the adhesion layers 222, 223 has at least oneadhesion surface (not shown). After removing the protection layers 224,225, the adhesion surface of the adhesion layer 222 or 223 is exposed,and a substrate 250 can be adhered to the belt 220 having microfluidicchannels 240. In detail, when one of the adhesion layers 222 or 223 hasbeen adhered to the substrate 250, the other adhesion layer can be usedto be adhered to another substrate 260. A plurality of holes 261 areformed on the substrate 260 for injecting a fluid into the microfluidicchannels 240.

The belt 220 can have various structures. For example, the intermediatelayer 221 of the belt 220 can be removed, thus the belt 220 can onlyhave one adhesion layer 222. At the time, a patterned microfluidicchannel 240 can be formed by cutting through the adhesion layer 222 bythe knife 211.

FIG. 4 is a structural view showing a complete product fabricated by thefabricating method of FIG. 2. In FIG. 4, reaction electrode 251 isdisposed on the substrate 250. The reaction electrode 251 can beconnected to an outer device in order to perform testing and analysis.The microfluidic structure 200 made by the method of the presentdisclosure is successfully applied on analyzing proteins and stem cellson the blood of human, and the analyzing results went well.

FIG. 5 is a schematic view showing another embodiment of the method ofFIG. 2. In the microfluidic structure 200 of FIG. 2, the micro fluidicchannel 240 is formed by cutting the belt 220 via the knife mold 210.Owing to the progress on the manufacturing technology, a width of theknife 211 of the knife mold 210 can be lower than 1 mm, and it issufficient to meet requirements of biomedical applications. However, forextending the application field of the microfluidic structure 200, toachieve lower line-width of the microfluidic channel 240 is necessary.In FIG. 5, a microfluidic structure 300 with ultra-small line-width isshowed. The microfluidic structure 300 includes a first microfluidicchannel 310 with larger line-width and a second microfluidic channel 320with smaller line-width.

The method for fabricating the first microfluidic channel 310 is thesame as that of the microfluidic channel 240.

After fabricating the microfluidic channel 310, an accommodating space311 is formed thereon. The second microfluidic channel 320 is formed inthe accommodating space 311 by a photolithography process or a screenprinting process. Finally, the microfluidic structure 300 is formed byadhering a substrate (not shown) to the first microfluidic channel 310.Owing to the second microfluidic channel 320 is formed by aphotolithography process or a screen printing process, a line-widththereof can be achieved to μm order. Therefore, issue on insufficientresolution for the microfluidic channel 240 of the microfluidicstructure 200 in FIG. 2 can be solved.

FIG. 6A to FIG. 6C are schematic views showing a method for fabricatingmicrofluidic structures 400 according to another embodiment of thepresent disclosure. In FIG. 5, the microfluidic structure 300 iscomposed of the first microfluidic channel 310 with larger line-widthand the second microfluidic channel 320 with smaller line-width.Therefore, to correctly align and combine two microfluidic channels withdifferent line-width is a critical problem. In FIG. 6C, the microfluidicstructure 400 includes a first microfluidic channel 410 with largerline-width and a second microfluidic channel 420 with smallerline-width. The first microfluidic channel 410 is formed by cutting thebelt 411. The second microfluidic channel 420 is patterned by aphotolithography process or a screen printing process, thus a pattern422 is formed on the substrate 421. An aligning area 412 is formed on aportion of the belt 411 where the first microfluidic channel 410located. The aligning area 412 includes an indentation 412 a. Analigning mark 423 is formed on the substrate 421. A position of thealigning mark 423 is corresponded to a position of the aligning area412. While the first microfluidic channel 410 is adhered with the secondmicrofluidic channel 420, the aligning mark 423 that projects thesubstrate 421 is aligned to the indentation 412 a. Therefore, thepattern 422 can be precisely embedded into an accommodating space 413,and the microfluidic structure 400 is formed.

From FIG. 6A to FIG. 6C, an easy and rapid method for fabricating themicrofluidic structure 400 is provided. In one example, in a situationthat without any supporting tools (e.g. microscope), the firstmicrofluidic channel 410 and the second microfluidic channel 420 can berapidly adhered with each other only by hand in accordance with thealigning mark 423. Furthermore, the aligning error can be less than 50μm.

FIG. 7A is a schematic view showing a method for fabricatingmicrofluidic structures 500 according to still another embodiment of thepresent disclosure; and FIG. 7B is a schematic view showing anotherexample of the folding line 540 of FIG. 7A. In FIG. 7A, a belt 530 iscut into two portions, a microfluidic channel 510 and an aligning mark520. The belt 530 is a double-sided tape. The structure of the belt 530is similar to the belt 220 in FIG. 2. The aligning mark 520 and themicrofluidic channel 510 are formed by cutting a protection layer (notshown) and an adhesion layer (not shown) of the belt 530. A hole 531 isformed by cutting through the belt 530 for injecting a fluid. After themicrofluidic channel 510 and the aligning mark 520 are formed, acomplete microfluidic structure 500 can be formed by aligning andfolding the microfluidic channel 510 and the aligning mark 520. Inaddition to that the aligning mark 520 can be embedded into themicrofluidic channel 510; a folding line 540 is also formed when cuttingthe belt 530. By a positioning functionality of the folding line 540,the aligning mark 520 and the microfluidic channel 510 can be preciselyfolded and adhered. Therefore, the stacking error can be reduced.

In FIGS. 7A and 7B, it is showed that by the folding line 540, thealigning mark 520 and the microfluidic channel 510 can be rapidly andprecisely aligned without any supporting tools (e.g. microscope). Forexample, the microfluidic structure 500 can be formed by hand within 5sec. Furthermore, by the folding line 540, the stacking error can beless than 1 μm. In FIG. 6A to FIG. 6C, only the aligning mark 423 isutilized for stacking and forming microfluidic structure 400. In FIG. 7Aand FIG. 7B, by utilizing the folding line 540, the precision ofalignment can be further enhanced, and stacking error can be reduced.

Furthermore, the folding line 540 can include an indentation 541 and aconnecting portion 542. In FIG. 7B, a length of the connecting portion542 can be less than 1 mm, and a thickness of the connecting portion canbe two times than that of the belt 530. Therefore, when stacking andadhering the aligning mark 520 and microfluidic channel 510, by thespecially designed folding line 540, the precision of alignment ishigher while it is only performed by hand. In one example, twomicrofluidic channels with different line-width can be formed on twoportion of belt 530 which is divided by the folding line 540. Byutilizing the aligning mark 520 and the folding line 540, the twomicrofluidic channels with different line-width can be stacked forforming a complete microfluidic structure.

FIG. 8 is a schematic view showing a method for fabricating microfluidicstructures 700 according to further another embodiment of the presentdisclosure. In FIG. 8, a belt 710 is cut and includes a first portion711, a second portion 712 and a third portion 713. The first portion 711is cut through, the second portion 712 is only cut off the protectionlayer 712, and the third portion 712 is cut off the protection layer andthe adhesion layer. Therefore, the microfluidic structure 700 can beeasily formed, and the alignment procedure can be performed under asmall line-width structure.

FIG. 9 is a schematic view showing a method for fabricating microfluidicstructures 800 according to one embodiment of the present disclosure. InFIG. 9, the microfluidic structure 800 is formed by stacking a firstbelt 820, a second belt 830, a third belt 840 and a fourth belt 850. Thefirst belt 820, the second belt 830, the third belt 840 and the fourthbelt 850 are a double-side tape or a single-sided tape respectively. Afirst microfluidic channel 821, a second microfluidic channel 831, athird microfluidic channel 841 and a fourth microfluidic channel 851 areformed in order on the first belt 820 to the fourth belt 850respectively via cutting by a knife mold. The first microfluidic channel821 has a first depth 822, the second microfluidic channel 831 has asecond depth 832, the third microfluidic channel 841 has a third depth842, and the fourth microfluidic channel 851 has a fourth depth 852. Thefirst depth 822, the second depth 832, the third depth 842 and thefourth depth 852 can be the same or different. For example, the firstdepth 822, the second depth 832, the third depth 842 and the fourthdepth 852 can be respectively adjustable between 30 μm to 400 μm.Therefore, microfluidic channels with various depths can be formed inthe microfluidic structure 800 by stacking the first microfluidicchannel 821 to the fourth microfluidic channel 851. In FIG. 9, a fluidcan have at least three degree of flow in the microfluidic structure800, thus the application field can be extended. The microfluidicstructure 800 is made by double-sided tapes or single-sided tapes;therefore it is easy to adhere a substrate 810 on a bottom side of thefirst belt 820 and another substrate 860 on a top side of the fourthbelt 850. A hole 870 is formed on the substrate 860 and connected witheach microfluidic channel for injecting the fluid.

To sum up, an easy and rapid method for fabrication microfluidicstructures is provided in the present disclosure. By cutting a belthaving adhesion layers (e.g. double-sided tape), the microfluidicstructure can be formed directly on the belt, and a completemicrofluidic device can be formed via the adhesion layers. Therefore,the whole process has advantages on simple materials, rapid fabricatingprocess and low cost. The method for fabricating microfluidic structuresof the present disclosure can solve issues on the complicatedfabricating process for the conventional microfluidic structure, and isespecially suitable for biomedical applications, such as extraction ofproteins or stem cells.

Although the present disclosure has been described in considerabledetail with reference to certain embodiments thereof, other embodimentsare possible. Therefore, the spirit and scope of the appended claimsshould not be limited to the description of the embodiments containedherein.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentdisclosure without departing from the scope or spirit of the disclosure.In view of the foregoing, it is intended that the present disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims.

What is claimed is:
 1. A method for fabricating microfluidic structures,comprising: providing a first belt and forming an adhesion layer on atleast one surface of the first belt; cutting the first belt for forminga first microfluidic channel, wherein the first microfluidic channelcomprises a first depth; providing a second belt and forming an adhesionlayer on at least one surface of the second belt; cutting the secondbelt for forming a second microfluidic channel, wherein the secondmicrofluidic channel comprises a second depth; adhering the first beltand the second belt via the adhesion layer of the first belt and theadhesion layer of the second belt; and stacking the first belt and thesecond belt in order to stack the first depth and the second depth. 2.The method of claim 1, wherein the first depth is different from thesecond depth.
 3. The method of claim 1, wherein the first depth or thesecond depth is ranged from 30 μm to 400 μm respectively.